1. Field of the Invention
The present invention relates to a radial compliance scroll compressor, and more particularly, to a radial compliance scroll compressor for minimizing friction loss and leakage loss between wraps of an orbiting scroll and a fixed scroll.
2. Description of the Background Art
Conventionally, a compressor converts a mechanical energy into a compression energy of compressible fluid, and it is classified into a reciprocating type, scroll-type, centrifugal-type(generally, turbo-type), and vane-type(generally, rotary-type). Among them, unlike the reciprocating-type compressor using a piston, the scroll-type compressor has a structure in which gas is sucked, compressed, and discharged by using a rotating body as the centrifugal-type and vane-type.
Such a scroll-type compressor is divided into a fixed radius scroll compressor which is configured such that an orbiting scroll orbits around the same radius all the time regardless of changes in compressing conditions, and a radial compliance scroll compressor which is configured such that the orbiting scroll goes backward in a radial direction, and then returns to the original status in order to prevent wraps from being damaged when liquid refrigerant, oil, or impurities are flowed into a compression chamber to thus abnormally increase pressure in the compression chamber.
To vary the orbital radius of the orbiting scroll in this radial compliance scroll compressor, the methods of inserting a slide bush or slide block, or an eccentric bush between the crank shaft and the orbiting scroll are commonly known. Among them, the present invention relates to a radial compliance scroll compressor for intervening an eccentric bush.
As illustrated in FIG. 1, such a radial compliance scroll compressor is configured such that: a main frame 2 and a sub frame 3 are fixed at both upper and lower sides of the inner circumferential surface of a casing 1 filled with oil at an adequate height; a driving motor 4 having a stator 4A and a rotor 4B is fixedly installed between the main frame 2 and the sub frame 3; a crank shaft 5 is forcibly inserted into the center of the rotor 4B of the driving motor 4 through the main frame 2; an orbiting scroll 6 having an involute wrap 6a and being eccentrically coupled to the crank shaft 5 is orbitably installed on the upper portion of the main frame 2; a fixed scroll 7 having an involute wrap 7a engaged with the wrap 6a of the orbiting scroll 6 to form a plurality of compression chambers is fixedly installed at the periphery portion of the main frame 2 on the upper surface of the orbiting scroll 6; and a discharge cover 8 dividing the interior of the casing 1 into a discharge pressure area, i.e., a high pressure portion, and a suction pressure area, i.e., a low pressure portion, is fixed to the inner circumferential surface of the casing 1 at the upper side of the fixed scroll 7.
At the front end surface of the crank shaft 5, a driving pin portion 5a for eccentrically rotating the orbiting scroll 6 is eccentrically protruded, and an oil passage 5b slantingly extends through the center of the driving pin portion 5a to the lower end of the crank shaft 5.
As illustrated therein FIG. 2, an eccentric bush 9 inserted into a boss portion 6b of the orbiting scroll 6 for thereby retreating the orbiting scroll 6 in a radius direction upon abnormal compression is eccentrically inserted into the driving pin portion 5a, and a stopper pin 10 for restricting the rotational movement of the eccentric bush 9 is inserted into the eccentric bush 9 so that it has a predetermined radial movable range.
More specifically, the upper half portion of the stopper pin 10 is inserted into to the eccentric bush 9, and the lower half portion thereof is movably inserted into a stopper groove 5d provided at the front end surface 5c of the crank shaft 5.
In the drawings, unexplained reference numeral 2a designates a through hole forming a radial bearing surface of the crank shaft 5.
The thusly configured scroll compressor in the conventional art will be operated as follows.
That is to say, the rotor 4B orbits the orbiting scroll 6 while being rotated together with the crank shaft 5 in the interior of the stator 4A by an applied power. At the same time, the orbiting scroll 6 undergoes an orbiting motion at a distance of the orbital radius from the pivot of the shaft by an Oldham ring(not shown) to thus form a plurality of compression chambers between the two wraps 6a and 7a. The volume of the compression chamber is reduced as the compression chambers move toward the center by a continual orbital motion of the orbiting scroll 6, resulting in discharging of sucked gaseous refrigerant.
At this time, in the case that the gaseous refrigerant flowed into the compression chamber remains in a normal state, the wrap 6a of the orbiting scroll 6 and the wrap 7a of the fixed scroll 7 contact with each other to thus form a closed space in the compression chambers at both sides, thereby making the eccentric bush 9 and the stopper pin 10 keep their position as shown in FIG. 4A. On the contrary, in the case that the gaseous refrigerant flowed into the compression chambers contains more than a predetermined amount of liquid refrigerant, oil, or other impurities as described abovexe2x96xa1xe2x96xa1, the pressure of the compression chamber is abnormally increased to make the orbiting scroll 6 tend to go backward. This tendency of going backward is delivered to the eccentric bush 9 inserted into the boss portion(shown in FIG. 2) 6b of the orbiting scroll 6. This eccentric bush 9 is rotated in the counterclockwise direction (the direction in which the orbiting scroll goes backward) until it reaches the stop position of the stopper pin as shown in FIG. 4B, and the wrap 6a of the orbiting scroll and the wrap 7a of the fixed scroll are isolated from each other. At this time, compression gas in a high pressure compression chamber(HR) is leaked into a low pressure compression chamber(LR), and then the wrap 6a of the orbiting scroll is restored to the original state, thus preventing the damage to the wraps 6a and 7a due to an However, in the conventional scroll compressor as described above, since the stopper pin 10 is provided at a predetermined interval from the driving pin portion 5a, the diameter(D1) of the crank shaft 5 must be formed larger than the gap between the stopper pin 10 and the driving pin portion 5a as illustrated in FIG. 3. In addition, the diameter of the through hole 2a of the main frame 2 supporting thcrank shaft in a radius direction also become larger for thereby increasing the frictional area between the crank shaft 5 and the main frame 2. Therefore, there occurs a problem that the motor efficiency is degraded due to friction loss during driving of the compressor as well as the material cost is increased.
Accordingly, it is an object of the present invention to provide a radial compliance scroll compressor capable of minimizing friction loss between a main frame and a bearing surface by decreasing the diameter of a crank shaft.
To achieve the above object, there is provided a radial compliance scroll compressor according to the present invention, where two scrolls having involute wraps are engaged with each other, the orbiting scroll of the two scrolls having a boss portion eccentrically coupled to a driving pin portion formed on the front end surface of a crank shaft undergoes an orbiting motion to thus form a plurality of compression chambers whose positions are continually moved between the two wraps, and the orbiting scroll coupled to the crank shaft goes backward in a radial direction within a predetermined range to thus isolate the wraps of the two scrolls from each other and then return to the normal state, thereby forming a compression chamber, which is characterized in that: an eccentric bush is inserted between the outer circumferential surface of the driving pin portion of the crank shaft and the inner circumferential surface of the boss portion of the orbiting scroll coupled thereto to be rotatably and eccentrically coupled to the crank shaft; a stopper pin restricting the radius movement of the eccentric bush is inserted between one side portion of the outer circumferential surface of the driving pin portion and the opposing inner circumferentical surface of the eccentric bush; and a stopper latch surface closely attached to the outer circumferential surface of the stopper pin and restricting the rotational movement of the eccentric bush and thusly the radius backward movement of the eccentric bush along with the orbiting scroll within a predetermined range.
In addition, in the radial compliance scroll compressor according to the present invention, it is preferred that the stopper latch surface of the driving pin portion is formed in a D-cut shape so that the stopper pin is slidably and linearly latched thereto in the backward direction.
In addition, in the radial compliance scroll compressor according to the present invention, it is preferred that an elastic member for elastically supporting the scrolls whose eccentric bush undergoes orbiting motion all the time is provided between the stopper latch surface and the corresponding stopper pin.